Smart-growth advocates, unions, and environmentalists had been excited by President Barack Obama’s $556 billion proposal for the six-year transportation bill, but [Committee Chairman John] Mica’s plan offers a mere $230 billion because Republicans are unwilling to raise the gasoline tax, which pays for federal transportation spending. They are also unwilling to create new sources of funding such as a tax on vehicle miles traveled (this would be achieved using GPS monitoring). But gasoline-tax revenues are actually declining, not just holding steady, because of lower usage during the recession and increasing vehicle efficiency. Whereas President George W. Bush was happy to cover the shortfall between gas-tax revenues and authorized transportation spending by taking money from general funds, these newly principled Republicans won’t do that. So per-year spending on transportation would decline from $52 billion to $35 billion per year when it should be going up to meet our growing needs.

The commitment to squeezing domestic discretionary spending, however, is more important to House Republicans. Mica actually supports raising funds for transportation—he co-sponsored a much larger proposal with former Chair Jim Oberstar last year—but he cannot get Republican support for it in the current environment. “He’s collared by the fact that the Ryan budget only allows this much money for [transportation],” says David Burwell, author of a recently released comprehensive report on surface transportation reauthorization from the Carnegie Endowment.

Obviously Mica has nobody but himself to blame for this. Republican members of Congress who didn’t like the consequences of Ryan’s budget could and should have refused to vote for it. Instead, we’ve got this.